I. Field of the Invention
The present invention relates generally to mufflers of the type which is connected to the exhaust pipe of an internal combustion engine.
II. Description of Related Art
A major goal of automotive manufacturers when selecting components used in the manufacture of the automotive vehicle is to select components that are both inexpensive and lightweight. The use of inexpensive components reduces the overall manufacturing cost of the vehicle while lightweight components improve fuel efficiency and reduce fuel consumption.
The muffler forms one component for automotive vehicles driven by internal combustion engines which is both relatively heavy and relatively expensive. As such, the cost of the muffler for an internal combustion engine driven automotive vehicle forms a significant part of the overall cost of the vehicle and also plays a significant factor in the fuel efficiency for the vehicle.
In order to reduce both the cost and weight of the muffler, there has been increased interest in developing a muffler having a housing that is constructed of a plastic, i.e. synthetic material, in view of both the low weight and low cost of such plastic material. Furthermore, plastic materials may be inexpensively molded as opposed to metal stamping commonly used to construct metal muffler housings.
In order to minimize the leakage of both exhaust products as well as noise from the muffler, it is necessary that a good seal be created between the exhaust pipe from the engine and the corresponding inlet to and outlet from the plastic muffler. While ideally the inlet to the plastic muffler would be dimensioned to snugly fit around the exhaust pipe, due to manufacturing tolerances for both the inlet as well as the exhaust pipe, it is difficult to achieve a snug fit between the exhaust pipe and the inlet and outlet to a plastic muffler that is sufficient to meet the automotive noise and exhaust leakage requirements of the automotive industry.
Consequently, there have been previous attempts to seal the exhaust pipe to the inlet and outlet of a plastic muffler by utilizing seals, gaskets, mastics, glues, adhesives, mechanical fasteners, and the like. All of these sealing methods, however, have their own disadvantages.
For example, the use of a gasket or a seal creates an additional component and thus an additional cost for the vehicle. Similarly, the use of glue, adhesives, etc. to seal the exhaust pipe to the inlet and outlet of a muffler having a plastic housing also increases the overall cost of the muffler system due to the cost of the glues or adhesives. Furthermore, the use of glues, adhesives, etc. also creates additional assembly time to construct the automotive vehicle thus increasing the overall manufacturing cost.